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