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