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