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