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