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