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