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