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