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