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