The colorless creature card stays revealed until Titan’s Presence leaves the stack.

The colorless creature card you reveal doesn’t have to still be in your hand as Titan’s Presence resolves. If it’s not, use its power as it last existed in your hand.

Check the target creature’s power as Titan’s Presence resolves to see if it’s less than or equal to revealed creature card’s power. If it’s greater, Titan’s Presence will finish resolving with no effect.