Be the thing off of which the echoes bounce
Color is one of the great mysteries, because it doesn’t really exist. When we say something is green, it isn’t a description of an inherent property of the thing, outside of its having a micro topology that, for reasons that are literally opaque, reflects some green light and absorbs most of the rest of the spectrum. The physical thing we call green is actually everything but. It’s more accurately described as green light resistant. The color of sunscreen is ultraviolet, which means that to birds with tetrachromatic eyes, everybody at the beach might as well be a member of Blue Man Group. Color is a property of the light reflected, as interpreted via the umvelt of the creature doing the perceiving, not a property of the thing being lit. From a mechanical standpoint, painting is about bouncing the right light back to humans.