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