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