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