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