The pic looks like the actual background for all the blocks is white/off-white, like muslin...the different colors look to be the rectangles around each block...I don't know that it would be considered sashing, but more like each star is a different color, then you have the muslin, and then each of those blocks you put different colors around the edges of each block...I love muslin, and think it will look great! Are you going to use batiks? Can you tell from the picture how many different colors there are? I imagine you can use whatever you like...personalize it to your tastes and such...maybe each center square of the star can be a different color, and then you use those same colors to edge around the muslin, in a design you choose..??..good luck, and hope you post a pic of what you decide..