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