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