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