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