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