if by stem words you mean the words that make up stem, the words are science, technology, engineering, math. say those in your head a couple times (or thousand times) which should help you memorize it.
I would just memorize a word for each prefix/suffix/root that uses it, along with the meaning. Seems easier and simpler than encoding 1-5 letters into a complex image, and then trying to attach the meaning of the root to it.
