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