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