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