Probably both, except within the bounds of easily 'random' bounds. Supposing it were possible for a mammal to be green, it wouldn't matter of green were 'better', unless it happened at the right time. Orange could have won out simply because it was good enough to do one thing (camoflauge for pretty) and didn't have enough downside to message that benefit (high visibility to hunters or less valuable prey). Heck, a gene that turned a lion invisible could have turned up and it wouldn't be guaranteed to carry forward even if it didn't have any downsides if the random recipient also happened to be clumsy or unlucky and died of some random injury or disease.

Evolution doesn't really have any tools that aren't random, at least until intelligence came around to provide other 'non natural' paths, though of course those are just as natural as the others, just that we think we're special and above nature.