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