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