# How to move nodes's names and emphasize arrow tips?

I am trying to draw a Cayley graph for Z_8 and need some arrows. My problems :

1. The names of nodes come exactly on the coordinators, is there a way of setting it to appear beside the coordinator not on it. Or, how can I move it manually up and down?
2. Because I fullback the nodes, the tips of arrows don't appear clearly. How can I solve it, even If I had to put the tip in the middle of the arrow. I appreciate any help or suggestions.

MWE:

\documentclass[12pt,letter]{article}

\usepackage{xcolor}
\usepackage{graphicx}

\usepackage{tikz}
\usetikzlibrary{arrows,shapes,positioning,mindmap,trees,automata}
\usepackage{amsfonts,amsmath,amsthm,epsf,graphics,verbatim,amssymb,amscd,eucal,bbm}
\newcommand{\Z}{{\mathbb Z}}
\begin{document}
\begin{figure}[h]
\begin{center}
\begin{tikzpicture}[line width=2pt]
%\draw [blue](2,.5) -- (3,.5) ; \draw [blue](-2,.5) -- (-3,.5) ;
%
%    \draw[style1] (0,0) -- ++( 1,0) coordinate (x);
%\draw[style2] (x)   -- ++( 0,1) coordinate (x);
%\draw[style3] (x)   -- ++(-1,0);
%

\draw[->,thick] (-1,1.8) -- (-2,.5);
\draw[->,thick, dashed](1,1.8)  -- (2,.5){};
%\draw[bend right,->,thin]  (1) to node [sloped,below] {$\mu(b)$} (3);
%\draw[bend right,->,thin]  (1) to node [sloped,above] {$\mu(a)$} (4);
%
\node (A) at (-1,1.8) {\;\;0};
\node (B) at (1,1.8) {\;\;1};
\draw[bend left,->,thin]  (A) to node [auto] {} (B);
%    \draw[->, to path={-| (\tikztotarget)}]

(A) edge (B);% (B) edge (C)  (C) edge (D);
\draw[fill=black] (-1,1.8) circle (0.1) ;
\draw[fill=black] (1,1.8) circle (0.1) ;
\draw[fill=black] (-2,.5) circle (0.1) ;

\draw[fill=black] (-2,-.8) circle (0.1) ;
\draw[fill=black] (2,.5) circle (0.1) ;

\draw[fill=black] (2,-.8) circle (0.1) ;
\draw[fill=black] (-1,-2.1) circle (0.1) ;
\draw[fill=black] (1,-2.1) circle (0.1) ;

\end{tikzpicture}
\end{center}
\caption{Cayley graphs on $\Z_8$ with generators set: $\{2,3\}$}
\label{polya Z^2}
\end{figure}

\end{document}