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