The symbolism is pretty direct, honestly. The covers I've seen often feature a lone figure—maybe a kid with his back turned—against a stark, empty background like a vacant lot or a cloudy sky. It's a visual shorthand for isolation, for being on the 'outside' looking in. I remember my old paperback had the two-toned red and yellow background. The red could be for anger or bloodshed, the yellow for fading innocence, maybe. The figures are never facing you, which makes the whole story feel like a private memory, something you're observing but not part of.
Then there's the stuff about sunset imagery. A lot of covers use those deep oranges and purples. That's the 'stay gold, Ponyboy' right there. It symbolizes something beautiful that can't last, the fleeting peace between the Socs and the Greasers. The art is usually uncluttered, almost lonely, which mirrors how Ponyboy feels even in a crowd—just him and his thoughts. The more minimalist the cover, the more it nails that feeling.