Believe they are call Bikini Covers, but honestly I've never tried to source one myself. As for custom colors, i'm guessing there isn't much of a market for them so they may not be available.
Assumption is the mother of all ****ups.
Know what you know, Know what you don't know. -Paul Pedzolt
"Jack of all trades, master of none, though oftentimes better than master of one" -Mynshul