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