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