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