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