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