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