If you don't find her, I made one years ago that is similar. Mine is just a plain knit a row, purl a row, knit a row blanket in stripes. Once that is done, you sew a single thread through the vertical stitches for the vertical lines. It's unbelivably simple. Mine was a tad different as the vertical lines were crocheted, not stitched. Crocheted makes a heavier line - I like the one above much better.
OK I just went and took a pic of mine. Mine also had some vertical color changes (the green). You can see the horizontal color changes in mine easy enough as you can see the stitches, and the vertical lines are done with a crochet hook.
The vertical lines in both afghans were done after knitting with either a needle or a crochet hook. I think that is what was throwing you off.
Hope this helps.