Set Theory in mathematics uses Venn Diagrams like this one to depict the proofs of theorems.

If you haven't already done so, first download the free trial version of RFFlow. It will allow you to open any chart and make modifications.

Once RFFlow is installed, you can open the above chart in RFFlow by clicking on Venn_Diagram.flo. From there you can zoom in, edit, and print this sample chart. It is often easier to modify an existing chart than to draw it from scratch.

To draw this chart without downloading it, run RFFlow and click on the More Shapes button, click the Circles stencil, and then click the Add Stencil button.