Of course nice / "proper" / usable Venn diagrams use only round(-ish) shapes so they are easy to decipher. If you stick to this limitation, you can visualize up to 3 sets in 2D (using circles), 4 sets in 3D (using spheres), then it gets tricky...
The 3D one works somewhat well if the spheres are translucent and animated.
https://en.wikipedia.org/wiki/Venn_diagram#Extensions_to_hig...