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