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