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