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