diff --git a/autodoc/doc_state.py b/autodoc/doc_state.py
index 13609ca..31a5b21 100644
--- a/autodoc/doc_state.py
+++ b/autodoc/doc_state.py
@@ -391,7 +391,7 @@ def __process_gamds__(name, cls, signals, edges):
             f"<{doc.format_name(sig_name)}> {sig_name} ({doc.type_to_string(sig_type)})"
         )
     if node:
-        node = f'{name} [label="{name}&#92;n{cls} | {node}", color=blue];\n'
+        node = f'{name} [label="{name}&#92;n{cls} | {node}", color=blue, style=filled, fillcolor=lightyellow];\n'
     return node, edges
 
 
@@ -532,13 +532,18 @@ def __state_full_graph__(label, state, app):
 def __simple_gam__(label, obj):
     cls = obj["Class"]
     id = f"fn{doc.format_name(label)}"
+    style = ""
+    if cls == "IOGAM":
+        style = ", style=filled, fillcolor=lightgray"
+    elif cls == "MessageGAM":
+        style = ", style=filled, fillcolor=yellow"
     if "InputSignals" in obj:
         for _, signal in obj["InputSignals"].items():
             ds = f'ds{doc.format_name(signal["DataSource"])}'
     if "OutputSignals" in obj:
         for _, signal in obj["OutputSignals"].items():
             ds = f'ds{doc.format_name(signal["DataSource"])}'
-    return f"{id}[label=<<B>{label}</B><BR/>{cls}>]\n"
+    return f"{id}[label=<<B>{label}</B><BR/>{cls}> {style}]\n"
 
 
 def __simple_ds__(label, obj, edges):