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