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