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