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