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