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