I did all my diagrams in Visio. I had experience with it so it was the simplest to implement.
All of my diagrams are available on-line http://mstewart.net/super8/visio/n687msvisio_files.htm for your viewing pleasure web enabled. I keep them on-line just in case I ever need them on the road.
Also if you want the actual Visio file, my POH and other useful items you can find them here http://mstewart.net/super8/
Enjoy,
Mike