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