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