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