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