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