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