At first glance, this is a simple image of the young Superman lifting a truck that had just fallen off of its jackstand. It's a strong image, with enough space under the truck to believe that it's really being lifted by a child. Considering it was done in the '70s using a crane instead of the CGI we're used to today, the effect is almost as surprising to us as it is to the Kents in the image.
At first glance, this is a simply composed image with just three main elements: the truck, the Kents, and the young Superman. However, there are two things happening in this image, each with a compositional structure of their own.
The first is simply what it appears like, with the future Superman lifting the truck off of the ground. While these elements naturally form a triangle, the truck itself perfectly aligns with the cross-image diagonal line of the Golden Triangle, a line that runs in between the child's grip. The child, while not on the other corner diagonal, nearly parallels its angle exactly.
The second event in the image is the Kents realizing that the young child they found is not of this world. Considering they're laying on the ground, on the other side of the truck from the camera, they take up a very small proportion of the image. Of course, discovering you're not alone in the universe would likely make you feel small also. While this works for the story, it does make for a creative problem, as the viewer's attention still needs to be drawn to them somehow. In this case, the Kents are framed with the child on one side, the ground below them, and the truck sloping downwards above them. Like typical "frame-within-a-frame" compositions, this cages the viewer's eyes around our subject, i.i: the Kents.
Overall, the lighting is very neutral, in part due to the overcast sky. While this doesn't highlight any one area or create dynamic shadows around other areas, it allows for the proper exposure of the image. In any other lighting condition, the underside of the truck would be a black void that would've eaten a bigger portion of the frame than the Kents and the child combined. As it is, the underside of the truck is exposed well enough to not only make out enough details to add interest, but it lets the browns and tan colors through.
Superman's red, blue, and yellow colors are universally recognized. Any other color on him would be wrong, not necessarily because of any stylistic choice, but because of the psychology of those colors, and how they relate to his character. In the anthology series Superman: Red & Blue, Lois Lane explains that red is meant to symbolize love, including a deep love for humanity and the planet Superman protects. It also represents fire and the righteous anger sometimes needed to save the day. Blue symbolizing the life-giving elements like water, but also the melancholy that balances the crimson-tinged anger. Together, they represent the blood that links all living things. Finally, in standard color theory, yellow represents hopeful optimism, which can stand for Superman's belief in the inherent goodness of humanity.
This image, although not very saturated, has only those same three colors in it. A dark red truck, faint blue sky, and the light tans of the soil and bags on the truck. Considering this is Superman's first demonstrated use of his powers, and he's using them to save people that are still basically strangers to him, the coloring shows he's on the way to becoming the Superman we all know. This is further foreshadowed by the bright red cloth that's wrapped around the child, almost as though it were the red cape he'll one day wear.
From a compositional standpoint, the bright red towel serves a second function. By being more vivid than anything else in the scene, it draws the viewer's eyes towards the child, enabling us to look on at his feat of strength with the same awe as the Kents.