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