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