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