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