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