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