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