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