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