I wanted to make different patterned but same coloured blankets for twin boys. I started with the stated pattern, but it was coming out much thicker than the other blanket, so I abandoned it and instead just used the idea of cascading colour rows in a basic 12-stitch repeating ripple granny pattern.
Because I wanted to make sure I had enough yarn for both, and that the colours used in each were roughly of the same balance (between the 2 blankets), I worked out colour distribution in an Excel spreadsheet - see the included screen clipping!
The basic pattern for the cascading colours was:
A-B-A-B-A-C-A-C-A-C-A-D-A-D-B-C-B-C-B-D-B-D-C-D, where A was the darker blue, B the light blue, C the mauve and D the yellow. And then I repeated that 3 more times.
Once I'd done all the ripples, I squared it off in the lighter blue, with a sequence of stitches in the "valleys": slip-sc-hdc-dc-htr-tr-tr-htr-dc-hdc-sc-slip (US terms) (or something like that anyway) & sc stitches on sides.