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