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