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