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