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