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