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