{ \newcommand{\nodea}{\node[draw,circle] (a) {$r$}
;}\newcommand{\nodeb}{\node (b) {$t_1$}
;}\newcommand{\nodec}{\node (c) {$t_k$}
;}\newcommand{\noded}{\node (d) {$...$}
;}\newcommand{\nodee}{\node[draw,circle] (e) {$s$}
;}\newcommand{\nodef}{\node (f) {$t'_1$}
;}\newcommand{\nodeg}{\node (g) {$t'_k$}
;}\newcommand{\nodeh}{\node (h) {$...$}
;}\begin{tikzpicture}[auto]
\matrix[column sep=.3cm, row sep=.3cm,ampersand replacement=\&]{
         \& \nodea  \&        \&        \& \\ 
 \nodeb  \& \noded  \& \nodec \& \nodee \& \\
         \&         \& \nodef \& \nodeh \& \nodeg \\
};

\path[ultra thick, red] (a) edge (b) edge (c) edge (e);
\path[dashed, red] (a) edge (d);
\path[ultra thick, red] (e) edge (f) edge (g);
\path[dashed, red] (e) edge (h);
\end{tikzpicture}}