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