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)(25,26,30,33)(27,32,34,31)(28,37,38,29)(35,36,40,39)(1,2)(3,6)(4,7)(5,8)(10,15)(11,18)(16,24)(19,21)(27,34)(31,32)(35,40)(36,39) involution — undirected(1,3)(2,5)(4,8)(6,7)(10,15)(11,18)(16,24)(19,21)(25,27,30,34)(26,31,33,32)(28,35,38,40)(29,36,37,39)(3,8)(5,6)(9,11)(10,12)(13,21)(14,18)(15,17)(16,22)(19,23)(20,24)(25,27)(26,32)(28,35)(29,39)(30,34)(31,33)(36,37)(38,40) 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)(25,28,30,38)(26,29,33,37)(27,35,34,40)(31,36,32,39)(1,3)(2,6)(4,8)(5,7)(9,13,14,23)(10,16,15,24)(11,19,18,21)(12,20,17,22)(25,29)(26,28)(27,36)(30,37)(31,35)(32,40)(33,38)(34,39)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.