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