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