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