If you go to the bobbincentral website, click on "Quilting" in the upper bar and the drop down list will have "color card" at the bottom of the top thread and bobbin thread lists.
Maybe this direct link will work:
http://www.bobbincentral.com/quiltin...lor-cards.html
Edit: It is also well worth checking out the accessories on the website. They have lots of items such as tweezers, bobbin cases, etc. at very low prices compared to others. Makes having extras on hand very affordable.