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