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