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