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