In the section expert you have a Color tab check background color, use the formula button on that tab to create a formula.
You would use an if statement something like (assumes that color is a string)...
If {datafield} = 'color' then crBlue;
You could use the rgb numbers for a custom shade of blue. This is available in CR2008, I have not looked at earlier verisons. However, it should get you close to what you are looking for.
Regards,
John W.