@ptss Revel’s white drivers are white because of the material, which in turn is due to performance metrics as selected by the designer(s).
@ghdprentice got it when he said painting will change 1 or > characteristic(s). Most posts mention a change in weight and that is surely accurate. However, the change would not be so limited. Paint whether wet or dry presents an acoustically disastrous surface insofar as microscopy would reveal. Flex and vibrational characteristics would be utterly destroyed. I say destroyed because likelihood of improving the sound with paint would be for the man who bets on a three-legged horse to discuss with you 😆
White drivers are usually aluminum- or ceramic-based or -coated. Neither of those materials should perform the same if covered in paint. Black drivers are black because of dye in the paper or the natural colors of carbon fibers or other reasons by design. That’s why even most flamboyantly hued bespoke speakers are generally still paired with non-color-coordinated (black) drivers: it’s no simple matter yet to change driver colors, due to matters in chemistry and physics.
Not a bad OP question IMO. The bad question (literally and figuratively) would’ve been “Why do my Revels sound bad after I changed / painted the drivers?” 😉
If driver aesthetics are that important, (1) grill or (2) another speaker model mentioned by others seem to be your logical options. Any coloring of the drivers is likely to… color… your speakers’ sound even more.