Sonya has posted a picture of Grace with this exact same hair, so perhaps they did play chess together or at least pose for this picture. Or it could be photoshop.

Setting that aside, two chess references that came to mind:
http://www.youtube.com/watch?v=j930o4CLU20
http://www.amazon.com/The-Kings-Chessboard-Picture-Puffins/dp/0140548807#reader_0140548807