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