Roo, I hate to break it to you, but her wings' colors aren't random. They follow the visible light color spectrum (ROYGBIV is commonly used to remember the basic way the colors change) with high energy (violet) nearest her and low energy (red) away from her. Or, at least that's the way it is in the reference image you provided. That looks like it's probably fanart, so I don't know if that's the way it actually is in the games (I've never played them). Just thought I'd point that out.