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