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