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