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