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