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