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