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