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