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