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