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