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