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)(11,15)(12,13)(14,16)(17,18)(19,23)(20,22)(21,24)(25,26)(27,31)(28,32)(29,30)(33,35)(34,39)(36,40)(37,38) involution — undirected(4,8)(6,7)(9,11,14,12)(10,15,16,13)(17,18)(19,23)(20,22)(21,24)(26,30)(31,33)(32,38)(39,40)(2,3)(6,7)(10,16)(11,12)(17,18,20,22)(19,21,24,23)(25,26)(27,33)(28,32)(29,30)(31,35)(34,40)(36,39)(37,38)(1,3,5,2)(4,7,8,6)(9,12,14,11)(10,15,16,13)(17,18)(19,21)(20,22)(23,24)(25,27,29,35)(26,31,30,33)(28,36,37,34)(32,40,38,39)(1,4)(2,6)(3,7)(5,8)(9,13,14,15)(10,11,16,12)(17,19,20,24)(18,21,22,23)(25,28,29,37)(26,32,30,38)(27,34,35,36)(31,39,33,40)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.