As one who graphs out nearly everything I do (my own designs usually), I agree with breaking out your graph paper.
Start by drawing one of your blocks, then adding the sashing you see around it on 2 adjoining sides;
draw the block next to it and the sashing added on its 2 adjoining sides;
fill in the difference as you see it in your picture.
With four blocks drawn (in a 4-patch configuration) you'll have the pattern for creating the sashings you want.
If you need to, PM me and I'll draw it out for you.
Jan in VA