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