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