Use your arrow buttons to navigate the racing gear menu and see where all the cursor winds up. Color selection is bottom-right once you've chosen a suite/helmet style and scrolling down the menu gives you the option to select/deselect color combinations. You'll find a "buy all" option at the bottom of the color combination list (30 or so combinations down from the top), which selects any color combination you've yet to purchase in that particular style at a prorated cost to account for the bundle. I don't believe there's a discount for buying them all at once.