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