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