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