I came up with a grid 9x9
B=background C= color
B-B-C-C-C-C-C-B-B
B-C-C-C-C-C-C-C-B
C-C-C-C-B-C-C-C-C
C-C-C-B-B-B-C-C-C
C-C-B-B-B-B-B-C-C
C-C-C-B-B-B-C-C-C
C-C-C-C-B-C-C-C-C
B-C-C-C-C-C-C-C-B
B-B-C-C-C-C-C-B-B
I think this might work - looks right on graph paper.