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