Four shapes arranged in a diamond: a green triangle (top), a purple square (left), a red circle (right), and a thick blue saltire (bottom). Each shape has a dim border of the same color. The triangle and saltire overlap the square and circle behind them.

I chose these particular shapes and colors because a Sony Playstation gamepad has four action buttons labeled with a green triangle, purple square, red circle, and blue saltire in the same cardinal directions.