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