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