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