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)(25,26,30,33)(27,35,37,29)(28,38,39,32)(31,34,40,36)(9,11,13,19)(10,14,15,17)(12,20,21,18)(16,24,23,22)(25,27,30,37)(26,29,33,35)(28,31,39,40)(32,34,38,36)(2,6)(7,8)(25,28,31,37,30,39,40,27)(26,32,34,35,33,38,36,29)(1,3,5,4)(2,7,6,8)(10,15)(14,17)(16,23)(22,24)(26,33)(29,35)(32,38)(34,36)(1,4,5,3)(2,8,6,7)(9,12,13,21)(10,16,15,23)(11,18,19,20)(14,22,17,24)(25,29,40,38,30,35,31,32)(26,27,36,39,33,37,34,28)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.