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