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