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