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