We use the following states:
%ground floor, basement,second floor, passing ground floor
\begin{itemize}
\item $s_g$ indicates that the elevator is on the ground floor.
\item $s_b$ indicates that the elevator is in the basement.
\item $s_s$ indicates that the elevator is on the second floor.
\item $s_f$ indicates that the elevator is passing the first floor.
\end{itemize}
The transition system is then given by: $\mathcal{T}$  = ($S$, $S_0$, $R$) with $S$ = $\{s_g, s_b, s_s, s_f\}$, $S_0$ = $\{s_g\}$, $R$ = $\{(s_g, s_g), (s_g, s_b), (s_b, s_b), (s_b, s_g), (s_g, s_f), (s_f, s_s), (s_s, s_s), (s_s, s_f), (s_f, s_g)\}$\\


\begin{center}
\begin{tikzpicture}[scale=0.2]
\tikzstyle{every node}+=[inner sep=0pt]
\draw [black] (13.9,-26) circle (3);
\draw (13.9,-26) node {$s_g$};
\draw [black] (27.8,-35.6) circle (3);
\draw (27.8,-35.6) node {$s_b$};
\draw [black] (27.8,-26) circle (3);
\draw (27.8,-26) node {$s_f$};
\draw [black] (27.8,-15.8) circle (3);
\draw (27.8,-15.8) node {$s_s$};
\draw [black] (4.8,-26) -- (10.9,-26);
\fill [black] (10.9,-26) -- (10.1,-25.5) -- (10.1,-26.5);
\draw [black] (11.501,-24.218) arc (261.13116:-26.86884:2.25);
\fill [black] (13.85,-23.01) -- (14.47,-22.3) -- (13.48,-22.14);
\draw [black] (16.37,-27.7) -- (25.33,-33.9);
\fill [black] (25.33,-33.9) -- (24.96,-33.03) -- (24.39,-33.85);
\draw [black] (26.957,-38.467) arc (11.34364:-276.65636:2.25);
\fill [black] (25.01,-36.67) -- (24.13,-36.34) -- (24.33,-37.32);
\draw [black] (25.33,-33.9) -- (16.37,-27.7);
\fill [black] (16.37,-27.7) -- (16.74,-28.57) -- (17.31,-27.75);
\draw [black] (16.9,-26) -- (24.8,-26);
\fill [black] (24.8,-26) -- (24,-25.5) -- (24,-26.5);
\draw [black] (27.8,-23) -- (27.8,-18.8);
\fill [black] (27.8,-18.8) -- (27.3,-19.6) -- (28.3,-19.6);
\draw [black] (28.483,-12.891) arc (194.52895:-93.47105:2.25);
\fill [black] (30.52,-14.57) -- (31.42,-14.86) -- (31.17,-13.89);
\draw [black] (27.8,-18.8) -- (27.8,-23);
\fill [black] (27.8,-23) -- (28.3,-22.2) -- (27.3,-22.2);
\draw [black] (24.8,-26) -- (16.9,-26);
\fill [black] (16.9,-26) -- (17.7,-26.5) -- (17.7,-25.5);
\end{tikzpicture}
\end{center}