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