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