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