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