loop through all cell in this active sheet
  if (cell has unapproved change) then
      set text color = red
  else 
      set text color = normal;
next cell

Sub HighlightCellWithUnApproveddChanges()
    Dim rwIndex As Integer
    Dim colIndex As Integer
    For rwIndex = 1 To 10
            For colIndex = 1 To 5
                If Cells(rwIndex, colIndex).XlCellChangeState = XlCellChangeState.xlCellChanged Then _
                    Cells(rwIndex, colIndex).Interior.ColorIndex = 36
            Next colIndex
    Next rwIndex
End Sub