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