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