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