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