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