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