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