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)(25,26,30,33,31,28,35,37)(27,32,34,39,29,36,38,40)(1,3,5,4)(2,6,8,7)(9,10,13,14)(11,18,17,15)(12,16,20,21)(19,24,23,22)(25,27,31,29)(26,32,28,36)(30,34,35,38)(33,39,37,40)(1,3,5,4)(2,7,8,6)(9,11,13,17)(10,15,14,18)(12,19,20,23)(16,22,21,24)(25,28)(26,31)(27,32)(29,36)(30,33)(34,40)(35,37)(38,39)(1,4,5,3)(2,6,8,7)(12,20)(16,21)(19,23)(22,24)(25,29,31,27)(26,32,28,36)(30,38,35,34)(33,39,37,40)(9,12,13,20)(10,16,14,21)(11,19,17,23)(15,22,18,24)(27,29)(32,36)(34,38)(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.