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