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