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