Colour code depending on range of values?

Colour code depending on range of values?

Is there a way to show different colours (colors) for a range of values that depends on the user's selection from a dropdown list? If so, how? And please provide step-by-step instructions.

Example: I have a field that has a range of values from 1-9 that is implemented as picklist type. For values between 1-3, I want to have it show as red, 4-6 as blue, 7-9 as green.