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)(11,19,21,17)(12,15,22,24)(13,23,20,18)(25,26)(27,33)(28,31)(29,32)(30,35)(34,39)(36,38)(37,40)(1,3,4,7)(2,5,6,8)(9,11,20,22,14,21,13,12)(10,15,23,17,16,24,18,19)(25,27)(26,30)(28,35)(29,34)(31,33)(32,38)(36,37)(39,40)(2,6)(5,8)(10,16)(11,21)(12,22)(18,23)(27,34)(29,37)(30,38)(32,40)(33,39)(35,36) involution — undirected(9,12,13,21,14,22,20,11)(10,17,18,15,16,19,23,24)(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.