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