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