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