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)(29,37)(33,38)(34,39)(36,40)(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)(27,28)(29,33)(30,31)(32,35)(34,36)(37,38)(39,40)(10,12)(11,13)(18,20)(19,21)(26,31)(28,35)(33,38)(36,40) involution — undirected(1,2,5,4)(3,6,8,7)(9,12,15,10)(11,17,13,16)(14,20,22,18)(19,24,21,23)(25,27,30,32)(26,28,31,35)(29,34,37,39)(33,36,38,40)(9,13,15,11)(10,17,12,16)(14,21,22,19)(18,24,20,23)(25,28)(26,32)(27,31)(29,36)(30,35)(33,39)(34,38)(37,40)(1,4,5,2)(3,7,8,6)(9,14,15,22)(10,18,12,20)(11,19,13,21)(16,23,17,24)(25,29)(26,33)(27,34)(28,36)(30,37)(31,38)(32,39)(35,40)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.