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