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