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)(11,14)(12,17)(13,16)(15,20)(18,22)(19,24)(21,23)(25,26,29,32)(27,30,33,37)(28,35,36,31)(34,40,39,38)(2,6)(3,7)(9,10)(11,14)(12,15)(13,16)(17,20)(18,22)(19,23)(21,24)(27,33)(30,37)(34,39)(38,40) involution — undirected(1,3,5,7)(2,4,6,8)(10,11)(15,17)(16,18)(23,24)(25,26)(27,30)(28,31)(29,32)(33,37)(34,38)(35,36)(39,40)(1,4)(2,7)(3,6)(5,8)(9,11,14,10)(12,17,20,15)(13,16,22,18)(19,23,21,24)(25,27)(26,30)(28,34)(29,33)(31,38)(32,37)(35,40)(36,39)(9,12,14,20)(10,15,11,17)(13,21,22,19)(16,24,18,23)(25,28,29,36)(26,31,32,35)(27,34,33,39)(30,38,37,40)(9,13,14,22)(10,16,11,18)(12,19,20,21)(15,23,17,24)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.