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