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