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