graph g {
    rankdir="LR";
    node [ shape="circle" ];
    {
        rank="same";
        J1;
        J2;
        J3;
        J1 -- J2 -- J3 [ style="invis" ];
    }
    {
        rank="same";
        B1;
        B2;
        B3;
        B4;

        B1 -- B2 -- B3 -- B4 [ style="invis" ];
    }
    J1 -- B1 [ penwidth=3 ];
    J1 -- B3;
    J1 -- B4;

    J2 -- B3 [ penwidth=3 ];
    J2 -- B4;

    J3 -- B2 [ penwidth=3 ];
    J3 -- B4;
}