I like this illustration, as it addresses TWO common misunderstandings. Recognizing that the payoff is in incomparable utilities is good. Even better is reinforcing that there can never be further iterations. None of the standard visualizations prevent people from extending to multiple interactions.

And it makes it clear that (D,D) is the only rational (i.e. WINNING) outcome.

Fortunately, most of our dilemmas repeated ones, in which (C,C) is possible.