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