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