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