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