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