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