Just found out:

Paul says in his 'Genius Mind' video that he learned it from Ron Davis's Gift of Dyslexia.

Additionally, check this out:
http://www.learningstrategies.com/forum/ubb/Forum8/HTML/002603.html

Also in the video, he says purpose of making it orange is because orange is an easy color to remember.

Now I wonder where Ron developed that technique...

-Jason