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