diff --git a/cluster_stats.py b/cluster_stats.py
index 4a19ec2..0e5a099 100644
--- a/cluster_stats.py
+++ b/cluster_stats.py
@@ -135,26 +135,46 @@ def stackplot(ax, x_signal, y_signals, legend_location='best'):
         ax.stackplot(x_signal, list(y_signals.values()))
         plt.legend(list(y_signals.keys()))
     else:
-        # emulating missing Axes.stackplot method
-        colors = get_rgb_palette(num_colors=len(y_signals), saturation=1.0, value=0.8)  # ['blue', 'orange', 'green', 'purple', 'yellow', 'cyan']
 
         # we sort the signals according to their labels to group departments of the same lab together on the plot
         ordered_y_signals = []
         ordered_labels = []
+        labs = set()
+        owner_to_lab = {}
         for label, y_signal in sorted(y_signals.items()):
             ordered_y_signals.append(y_signal)
             ordered_labels.append(label)
+            lab = label.split('.')[0]
+            labs.add(lab)
+            owner_to_lab[label] = lab
+
+        # instead of evenly spreading the colour in the spectrum, we try to separate groups of colors (1 group for a lab), to ease reading the graph
+        num_unused_colors_between_labs = 1
+        num_unused_colors = len(labs) * num_unused_colors_between_labs
+        num_owners = len(y_signals)
+        num_colors = num_owners + num_unused_colors
+        # emulating missing Axes.stackplot method
+        colors = get_rgb_palette(num_colors=num_colors, saturation=1.0, value=0.8)  # ['blue', 'orange', 'green', 'purple', 'yellow', 'cyan']
+
         y = np.row_stack(ordered_y_signals)
         # this call to 'cumsum' (cumulative sum), passing in your y data,
         # is necessary to avoid having to manually order the datasets
         y_stack = np.cumsum(y, axis=0)   # a 3x10 array
+        last_lab = None
+        color_index = 0
         for series_index in range(len(y_signals)):
             if series_index == 0:
                 from_signal = 0
             else:
                 from_signal = y_stack[series_index - 1, :]
-            ax.fill_between(x_signal, from_signal, y_stack[series_index, :], color=colors[series_index], lw=0.0)
-            p = plt.Rectangle((0, 0), 0, 0, color=colors[series_index])
+            owner = ordered_labels[series_index]
+            lab = owner_to_lab[owner]
+            color_index = (color_index + 1) % num_colors
+            if lab != last_lab:
+                color_index = (color_index + num_unused_colors_between_labs) % num_colors
+                last_lab = lab
+            ax.fill_between(x_signal, from_signal, y_stack[series_index, :], color=colors[color_index], lw=0.0)
+            p = plt.Rectangle((0, 0), 0, 0, color=colors[color_index])
             ax.add_patch(p)
 
         if legend_location == 'outside right':