Skitterskin

A card with devoid is just colorless. It's not colorless and the colors of mana in its mana cost.

Cards with devoid use frames that are variations of the transparent frame traditionally used for Eldrazi. The top part of the card features some color over a background based on the texture of the hedrons that once imprisoned the Eldrazi. This coloration is intended to aid deckbuilding and game play.

Skitterskin's activated ability doesn't depend on Skitterskin being colorless. If it gains one or more colors, you can still activate the ability if you control another creature that's colorless.