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