One vertex per element, one color per generator, with an edge from x to x·s.
(3,7)(5,8)(9,10)(11,16)(12,13)(14,18)(15,19)(17,24)(20,23)(21,22)(25,26)(27,33)(28,36)(29,32)(30,35)(31,37)(34,38)(39,40) involution — undirected(1,2,4,6)(3,5,7,8)(11,19)(15,16)(20,22)(21,23)(25,26,29,32)(27,30,35,33)(28,31,37,36)(34,38,40,39)(1,3)(2,5)(4,7)(6,8)(9,11,14,19)(10,15,18,16)(12,22,17,20)(13,23,24,21)(25,26,29,32)(27,33,35,30)(28,36,37,31)(34,38,40,39)(9,12,14,17)(10,13,18,24)(11,20,19,22)(15,21,16,23)(25,27,29,35)(26,30,32,33)(28,34,37,40)(31,38,36,39)(1,2)(3,5)(4,6)(7,8)(9,11)(10,16)(12,22)(13,21)(14,19)(15,18)(17,20)(23,24)(25,26)(27,33)(28,31)(29,32)(30,35)(34,39)(36,37)(38,40) involution — undirected(1,3)(2,5)(4,7)(6,8)(9,13)(10,17)(11,21)(12,18)(14,24)(15,22)(16,20)(19,23)(25,28,29,37)(26,31,32,36)(27,34,35,40)(30,38,33,39)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.