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