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