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