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