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