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