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