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