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