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