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