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