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