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