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