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)(25,26,31,37)(27,38,39,33)(28,36,30,34)(29,40,32,35)(9,11,13,19)(10,14,15,17)(12,20,21,18)(16,24,23,22)(25,27,31,39)(26,33,37,38)(28,32,30,29)(34,35,36,40)(2,5)(6,8)(25,28,32,39,31,30,29,27)(26,34,35,38,37,36,40,33)(1,3,4,7)(2,6,5,8)(10,15)(14,17)(16,23)(22,24)(25,29,31,32)(26,35,37,40)(27,28,39,30)(33,36,38,34)(9,12,13,21)(10,16,15,23)(11,18,19,20)(14,22,17,24)(25,30,29,39,31,28,32,27)(26,36,40,38,37,34,35,33)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.