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