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