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