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)(11,17)(12,16)(13,15)(14,18)(19,23)(20,22)(21,24)(25,26,29,34,31,28,30,33)(27,35,39,32,37,40,38,36)(1,3,5,4)(2,6,8,7)(9,11)(10,14)(12,19)(13,18)(15,17)(16,21)(20,24)(22,23)(25,27,31,37)(26,32,28,36)(29,38,30,39)(33,40,34,35)(1,3,5,4)(2,7,8,6)(10,15)(11,18)(16,22)(19,24)(25,28)(26,31)(27,36)(29,34)(30,33)(32,37)(35,38)(39,40)(1,4,5,3)(2,6,8,7)(9,12)(10,16)(11,19)(13,20)(14,21)(15,22)(17,23)(18,24)(27,37)(32,36)(35,40)(38,39)(12,20)(16,22)(19,24)(21,23)(25,29,31,30)(26,33,28,34)(27,38,37,39)(32,40,36,35)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.