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