Loop Through Widget Styles

I’m building a theme and what I’m trying to do is for each widget have a custom style applied. For example, the sidebar will have three text widgets. I want the title of the first widget to have a background of blue, the next widget title will have a background of green, and the third widget title will have a background of red, and if any new widgets are added the cycle will start over. I know you can accomplish this using a loop, but the widget before_title and after_title elements are defined in an array. Any ideas on how to accomplish this?