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