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