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