Hi mojo,
As you are probably aware, there is no built-in Venn diagram capability. However, with a bit if VBA code and the appropriate algorithms it is quite easy to overlap circles (or other Shape objects) to produce the exact amount of area overlap you want, and to shade them in such a way that, for example, the intersecting area displays in a different color than the color of either circle. Is this what you want?
Keep Excelling.
Damon