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