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