I have the following picture. I want to make the arrows a little bigger, so that there is enough space for F and G to be written, and the diagram look a little more beautiful. Can anybody help?
\documentclass[12pt]{article}
\usepackage{tikz, pgfplots}
\pgfplotsset{compat=1.10}
\usepgfplotslibrary{groupplots}
\begin{document}
\begin{center}
\begin{tikzcd}
\widehat{w}_{i} \arrow[maps to]{r}\arrow[maps to]{dr}[swap]{F } & x \widehat{w}_{i} \arrow[maps to]{r}\arrow[maps to]{dr}[swap]{F} & x^{2} \widehat{w}_{i} \arrow[maps to]{r} \arrow[maps to]{dr}[swap]{F} & x^{3} \widehat{w}_{i} \arrow[maps to]{r} & \ldots \arrow[maps to]{r} \arrow[maps to]{dr} & x^{d_{i}} \widehat{w}_{i} \\
& v_{i} \arrow[maps to]{u}[]{G}\arrow[maps to]{r}[]{}& x v_{i} \arrow [maps to] {r} \arrow[maps to]{u}{G}& xv_{2} \, \, \arrow[maps to]{u}{G} \arrow[maps to]{r} & \, \, \ldots \arrow[maps to]{r} & x ^ { d_{i} - 1} v_{i} \arrow[maps to]{u}{G}
\end{tikzcd}
\end{center}
\end{document}