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