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