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