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