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