Here's how I do it for 3-way Venn diagrams in PowerPoint 2K, to I think,
good effect.
I use regular hexagons for the circles. The 3-way intersection is an
over-laid smaller regular hexagon.
The 2-way intersections are very carefully over-laid block arrows (Right
Column, 5th from the top.) I had to rotate two of them.
Using Blue, Red and Yellow hexagons, you can make orange, green and
purple arrows/intersections, and the middle intersection whatever color
you choose. Fussy, but you have complete control.
Each set and intersection gets its own color for each is its own
autoshape. The end result is good-looking and modern.
Good Luck,
Hash