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