The diagram is of a flattened dodecahedron. Each face has five edges. There are 12 faces on a dodecahedron, and there are, coincidentally, 12 ways to seat 5 people at a round table (if you don't consider clockwise/counterclockwise to be important). Try to color the dodecahedron (by clicking on the edges) so that each face represents a different "seating arrangement".