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