Feynman diagrams by Edward Tufte
edwardtufte.com
edwardtufte.com
(I understand a bit about quantum physics; the book that helped me the most was Quantum Reality by Nick Herbert)
edited to add: I want to emphasize that I understand a tiny tiny bit of qp. I posted this comment hoping that there exists some analogue of Herbert's book for QED; a book which guides the motivated but non-physicist reader through the basics of the theory.
Here is a link to a 161 page pdf on QFT and QED (Warning: direct pdf download):
stanford.edu/~mukul/tutorials/Quantum_Optics.pdf
I have found his explanations of quantum physics to be very clear. [Edit: url correction]
It's his lectures and he was a good teacher.