You don't have to match the bike. But you still may want to get rid of the yellow stickers! My Merlin came with red stickers, which clashed with my pink King headset. A hair dryer, credit card and 30 minutes later--no more stickers.

I do plan to get some new stickers at some point, either from Merlin (the new Litespeed stickers are white) or make my own. I might try this place:
http://www.quickstickers.com/custom.php

I also want to get just a bit of bling to match my headset. Maybe some handlebar end caps and bottle cages.
http://www.purelycustom.com/c-31-road-bikes.aspx