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