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