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