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