documentclass[10pt]{book}
usepackage{tikz}
usepackage{pgfplots}
usepackage{capt-of}

begin{document}

begin{center}
    begin{tikzpicture}
    begin{axis}[legend pos=south east,
        xlabel style={align=center},
        xlabel={Horizontal Subgrade Modulus, (lb/in)/in},
        ymin=600,
        ylabel={Maximum Moment, lb-in (N-m)},
        height=0.3textheight,
        width=0.9columnwidth,
        cycle list name=mark list*,
        legend columns=2
        ]
            addplot [nodes near coords,mark=*, %S1
                visualization depends on=thisrow{alignment} as alignment,
                every node near coord/.style={anchor=alignment},
                point meta=explicit symbolic,]
                table [meta index=2]{
                    x   y   label   alignment
                    94  637 {footnotesize 637 (71.94)} -110
                    185 766 {footnotesize 766 (86.59)} -90
                    357 885 {footnotesize 885 (100.02)}    90
                };

        legend {S1}
    end{axis}
    end{tikzpicture}
    captionof{figure}{MAXIMUM MOMENT --- 4 IN. DIAMETER PIPE}
    label{4_Mom}
end{center}


end{document}

documentclass[preview]{standalone}

usepackage{pgfplots}
usepackage{caption}

begin{document}

begin{center}
    begin{tikzpicture}
    begin{axis}[legend pos=south east,
        xlabel style={align=center},
        xlabel={Horizontal Subgrade Modulus, (lb/in)/in},
        ymin=600,
        ylabel={Maximum Moment, lb-in (N-m)},
        height=0.3textheight,
        width=0.9columnwidth,
        cycle list name=mark list*,
        legend columns=2
        ]
            addplot [nodes near coords,mark=*, %S1
                visualization depends on=thisrow{alignment} as alignment,
                every node near coord/.style={anchor=alignment, fill=white},
                point meta=explicit symbolic,]
                table [meta index=2]{
                    x   y   label   alignment
                    94  637 {footnotesize 637 (71.94)} -110
                    185 766 {footnotesize 766 (86.59)} -90
                    357 885 {footnotesize 885 (100.02)}    90
                };

        legend {S1}
    end{axis}
    end{tikzpicture}
    captionof{figure}{MAXIMUM MOMENT --- 4 IN. DIAMETER PIPE}
    label{4_Mom}
end{center}


end{document}