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