One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,5)(7,8)(9,10)(11,16)(12,26)(13,19)(14,21)(15,20)(17,23)(18,29)(22,36)(24,31)(25,32)(27,35)(28,34)(30,37)(33,39)(38,40) involution — undirected(2,5)(6,8)(9,11,15,23,13,25,14,24)(10,16,21,31,19,32,20,17)(12,22,29,37,27,39,28,38)(18,30,26,36,34,40,35,33)(9,11)(10,17)(12,22)(13,25)(14,24)(15,23)(16,21)(18,33)(19,31)(20,32)(26,30)(27,39)(28,38)(29,37)(34,36)(35,40) involution — undirected(1,3,4,7)(2,6,5,8)(9,12,15,29,13,27,14,28)(10,18,21,26,19,34,20,35)(11,22,23,37,25,39,24,38)(16,30,31,36,32,40,17,33)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.