graph G {
    compound="true"
    rankdir="TB"
    bgcolor="white"
    fontname="Tahoma"

    node [
        fixedsize="false"
        fontname="Tahoma"
        color="white"
        fillcolor="grey"
        fontcolor="black"
        shape="box"
        style="filled"
        penwidth="1.0"
    ]
    edge [
        fontname="Arial"
        color="#00688b"
        fontcolor="black"
        fontsize="12"
        arrowsize="0.5"
        penwidth="1.0"
    ]




    "asonnino@fb.com" -- "alberto.sonnino@ucl.ac.uk" [label=" 49 ", penwidth="10", color="#00688bFF"];
    "mathieubaudet@fb.com" -- "asonnino@fb.com" [label=" 43 ", penwidth="8", color="#00688bDB"];
    "mathieubaudet@fb.com" -- "alberto.sonnino@ucl.ac.uk" [label=" 25 ", penwidth="5", color="#00688bA5"];

}