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