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