The Color List user interface allows a simple color selection on the Buyer Side. Displays all colors from the Designer Side as a drop-down menu for the Buyer to select from. You can select one or multiple color groups to define which colors should be shown in the drop down.
Only the colors of the selected groups will be displayed at the Buyer Side.
Another option to display a color selection at the Buyer Side is a Select List.
Read more about this option here
If you need to control a color change using a Style watch this video: