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