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