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