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