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