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