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