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