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