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