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