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