Formatting Based On Unique Value?

I'm trying to visually format my spreadsheet in a way that lumps customers together. Excel gives you the automatic "every other line" two tone variation.

(blue)
(blue)

(light blue)
(light blue)

(blue)
(blue)

[code]....

I've sorted by data by customer name. I want to format all Customer A rows as (blue), Customer B rows as (light blue), customer C (blue), customer D as (light blue) etc. With hundreds of customers and typically between 1-5 entries for each customer, this an impossibly time consuming task. Is there anyway to automate this process?

Customer A (Blue)

Customer A (Blue)

Customer B (light Blue)

Customer C (Blue)

[code]....