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