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