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