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