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