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