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