Can you connect 6 dots with 6 curves, such that every pair of curves touch each other exactly once? Curves can touch anywhere at their interior or at the dots, and the whole thing must lie in the plane.
RGB and CMY form two "triangles", so each of the groups of three is touching its other members - the only tricky part is making every side of one triangle touch the other triangle.
Cyan is tangent to Green at the spot it's supposed to touch, Magenta and Yellow are tangent to Blue.
Alternatively, if you actually need connectedness,