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