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