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