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