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