This site has a chart at the bottom. Your Star is only 8 blocks across, so if you want the star on top of a 60" wide mattress, the blocks will need to finish at 7 1/2". Then you can border it from there.
http://www.quiltfrog.com/fourhour.html
Isn't a queen mattress 60X80?
Here is my lap size one. The center has 6" finished blocks, so it was 48" and then I added from there. Not big enough for a queen, of course.
http://www.quiltingboard.com/t-158183-1.htm