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