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