Several options for the \Edge macro

\begin{tikzpicture} \SetVertexNormal \Vertex[x=0,y=2.5]{A} {\tikzstyle{every node} = [node distance=1.5cm] \Vertices[x=1.5,y=4,dir=\SO]{B,C,D}} \Vertices[x=3,y=5,dir=\SO]{E,F,G,H,I,J} \Vertices[x=4.5,y=5,dir=\SO]{K,L,M,N,O,P} {\tikzstyle{every node} = [node distance=1.5cm] \Vertices[x=6,y=4,dir=\SO]{Q,R,S}} \Vertex[x=7.5,y=2.5]{T} \Edges[color=red](A,B,E,K,Q,T,S,P,J,D,A) \foreach \x/\y in {E/F,G/H,I/J,K/L,M/N,O/P} {\Edge[color=green](\x)(\y)} \Edge[style=->](I)(P) \Edge[style=dashed](A)(C) \Edge[style=dotted](C)(F) \Edge[label=CD](C)(D) \Edge[label=BC,labelcolor=yellow](B)(C) \Edge[label=QR,labelcolor=orange,labeltext=cyan](Q)(R) \Edge[label=RS,labelstyle=right](R)(S) \Edge[label=OS,labelstyle={below=1pt,inner sep=0pt}](O)(S) \Edge[label=LQ,labelstyle={above,font=\bfseries}](L)(Q) \Edge[label=FL,labelstyle={font=\tiny\bfseries}](F)(L) \Edge[label=GN,labelstyle={sloped,above}](G)(N) \Edge[style={bend right}](A)(T)\end{tikzpicture}

See also: Original Source by Rafael