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