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