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