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