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