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