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