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