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