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