# draw graphs in tikz

\documentclass{book}
\usepackage{graphs}
\usetikzlibrary{graphs}

\begin{doument}
\begin{tikzpicture}[new set=import nodes]
\begin{scope}[nodes={set=import nodes}] % make all nodes part of this set
\node [red] (a) at (0,1) {$a$};
\node [red] (b) at (1,1) {$b$};
\node [red] (d) at (2,1) {$d$};
\end{scope}
\graph {
(import nodes);
% "import" the nodes
a -> b -> c -> d -> e;
};
\end{tikzpicture}
\end{document}


When I compiled this code, I got the error

! LaTeX Error: File graphs.sty' not found.

Type X to quit or <RETURN> to proceed,
or enter new name. (Default extension: sty)

Enter file name:

• Welcome! Do you have a package called graphs i.e. a file graphs.sty? Because I don't - it doesn't seem to be in TeX Live. – cfr Feb 6 '16 at 3:44

LaTeX can only load existent packages. If you try to load a non-existent one, it will complain with an error.

No graphs.sty exists on my system. I think the package you probably want is TikZ:

\documentclass{book}
\usepackage{tikz}
\usetikzlibrary{graphs}

\begin{document}
\begin{tikzpicture}[new set=import nodes]
\begin{scope}[nodes={set=import nodes}] % make all nodes part of this set
\node [red] (a) at (0,1) {$a$};
\node [red] (b) at (1,1) {$b$};
\node [red] (d) at (2,1) {$d$};
\end{scope}
\graph {
(import nodes);
% "import" the nodes
a -> b -> c -> d -> e;
};
\end{tikzpicture}
\end{document}
`