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