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