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