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