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