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