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