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