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