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