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)(11,17)(12,15)(13,16)(14,19)(18,23)(20,22)(21,24)(1,3,6,5)(2,7,4,8)(9,10,13,16)(11,14,19,17)(12,15,20,22)(18,21,24,23)(25,26,30,31)(27,29,33,38)(28,35,37,32)(34,40,39,36)(1,3,6,5)(2,8,4,7)(12,20)(15,22)(18,24)(21,23)(26,31)(29,38)(32,35)(36,40)(1,4,6,2)(3,7,5,8)(9,11)(10,14)(12,18)(13,19)(15,21)(16,17)(20,24)(22,23)(25,27,30,33)(26,29,31,38)(28,34,37,39)(32,36,35,40)(1,5,6,3)(2,7,4,8)(9,10)(11,14)(12,15)(13,16)(17,19)(18,21)(20,22)(23,24)(25,28,30,37)(26,32,31,35)(27,34,33,39)(29,36,38,40)(9,12,13,20)(10,15,16,22)(11,18,19,24)(14,21,17,23)(25,29)(26,33)(27,31)(28,36)(30,38)(32,39)(34,35)(37,40)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.