I don't understand what they mean by "diagram a game"...can you please help me with this?

Mr. and Mrs. Ward typically vote oppositely in elections and so their votes" cancel each other out. "They each gain two units of utility from a vote for their positions (and lose two units of utility from a vote against their positions). However, the bother of actually voting costs each one unit of utility. Diagram a game in which they choose whether to vote or not to vote.