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)(18,32,36,29)(22,38,40,35)(23,24,31,33)(27,37,39,34)(2,5)(6,7)(9,11,15,25)(10,17,19,21)(12,27,30,39)(13,31,20,23)(14,24,16,33)(18,35,36,38)(22,32,40,29)(26,34,28,37)(9,12,14,32,15,30,16,29)(10,18,13,28,19,36,20,26)(11,22,33,39,25,40,24,27)(17,34,23,38,21,37,31,35)(9,13,16,10,15,20,14,19)(11,23,24,17,25,31,33,21)(12,28,29,18,30,26,32,36)(22,38,27,34,40,35,39,37)(1,3,4,8)(2,6,5,7)(9,14,15,16)(10,13,19,20)(11,24,25,33)(12,29,30,32)(17,31,21,23)(18,26,36,28)(22,39,40,27)(34,38,37,35)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.