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