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