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)(11,17)(12,16)(13,15)(14,19)(18,24)(20,22)(21,23)(26,30)(27,34)(33,37)(35,38) involution — undirected(9,11,13,19)(10,14,15,17)(12,20,21,18)(16,24,23,22)(25,26)(27,32)(28,30)(29,37)(31,35)(33,36)(34,40)(38,39)(2,5)(6,8)(25,27,28,34)(26,31,30,39)(29,38,36,35)(32,33,40,37)(1,3,4,7)(2,6,5,8)(10,15)(14,17)(16,23)(22,24)(25,27)(26,32)(28,34)(29,35)(30,40)(31,37)(33,39)(36,38)(9,12,13,21)(10,16,15,23)(11,18,19,20)(14,22,17,24)(26,33)(27,34)(29,36)(30,37)(31,32)(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.