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