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