Newbee question on Venn diagrams

I’m trying to do some Venn diagrams in OmniGrafflePro. I’d like to be able to shade individual segments of the overlapping circles. That would seem to involve separate the diagram into its component shapes, but I don’t see a way to do this in OmniGraffle. I can create each segment individually with the combine/subtract shapes, but that seems unnecessarily tedious. Is there a more straightforward way of doing this?

I think the most straightforward way of doing this would be to set the opacity of the shapes to f.x 50% and choosing different colours for each shape.
Duplicating and intersecting the shapes would probably be my second choice.