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