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