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