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