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