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