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