Each node has an inner color and an outer color. The goal is to get the two colors of each node to match, by moving the inner colors around. The catch is that the only move you can do is a bit weird.

Select one node from each group of four, and press space. The inner colors of the other 3 nodes in the group will rotate in the direction of the arrows. You must always rotate both sides at once.

One more restriction is that you can't select two opposite nodes at the same time (the opposite node will be grayed out).