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