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