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