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