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