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