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