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