Don't know the pattern, but it looks like it is made from half square triangles. You may be able to draft it out on paper. Even though it has lots of fabrics in it, the pattern can be thought of as a two-color quilt. Color 1 is the lights and Color 2 is the darks.
Once you've sketched out the pattern on paper, just pick a square size that would make it be the size you're wanting.