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)(11,18)(12,22)(13,16)(14,17)(15,21)(19,20)(23,24)(25,26)(27,30)(28,31)(29,32)(33,35)(34,38)(36,37)(39,40) involution — undirected(1,3,4,8)(2,5,6,7)(9,10)(11,19)(12,16)(13,22)(14,17)(15,21)(18,20)(23,24)(25,27,29,35)(26,30,32,33)(28,34,37,40)(31,38,36,39)(9,11,12,21,14,20,13,23)(10,15,16,18,17,24,22,19)(25,26)(27,33,35,30)(28,36)(29,32)(31,37)(34,38,40,39)(2,6)(5,7)(11,20)(15,24)(18,19)(21,23)(25,28,29,37)(26,31,32,36)(27,34,35,40)(30,38,33,39)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.