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