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