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