\documentclass{standalone}
\standaloneconfig{border=2mm 2mm 2mm 2mm}

\usepackage{tikz}

\begin{document}
  \begin{tikzpicture}[scale=3]
    % Define the vertices
      \coordinate (A) at (0,0,1);
      \coordinate (B) at (3,0,1);
      \coordinate (C) at (3,0,0);
      \coordinate (D) at (0,0,0);
      \coordinate (E) at (0,1,1);
      \coordinate (F) at (3,1,1);
      \coordinate (G) at (3,1,0);
      \coordinate (H) at (0,1,0);

      % Draw the edges of the cube
      \draw (A) -- (B) -- (C); \draw[dashed] (C) -- (D) -- (A);
      \draw (E) -- (F) -- (G) -- (H) -- cycle; % top
      \draw (A) -- (E); \draw (B) -- (F); \draw (C) -- (G); \draw[dashed] (D) -- (H); % vertical

      % Label the vertices
      \foreach \vertex/\position in {A/below left,B/below right,C/above right,D/above left,E/above left,
        F/below right,G/above right,H/above left}
        {
          \fill (\vertex) node[\position] {$\vertex$};
        }
  \end{tikzpicture}
\end{document}