Example 0

Show[Plot3D[-1-x-y,{x,-5,5},{y,-8,8},PlotStyle->Red],Plot3D[-4-x+y,{x,-5,5},{y,-8,8},PlotStyle->Blue],Plot3D[-1+x-y,{x,-5,5},{y,-8,8},PlotStyle->Green],Plot3D[1+x+y,{x,-5,5},{y,-8,8},PlotStyle->White]]