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