\documentclass{standalone}
\usepackage{tikz}
\usepackage{tikz-qtree}
\usepackage{xcolor}
\usetikzlibrary{arrows}
\usepackage{fontspec}
\setmainfont{Helvetica}
\begin{document}
\begin{tikzpicture}
\tikzset{level distance=30pt}
\tikzset{every  leaf node/.style={text=blue,font=\bf}}
\tikzset{every internal node/.style={text=darkgray,font=\bf}}
\tikzset{edge from parent/.append style={thick}}

\Large

\Tree [.NP [.DET the ] [.N' [.ADJ little ] [.N' [.ADJ tiny ] [.N' [.ADJ cute ] [.N' [.ADJ black ] [.N' [.ADJ stray ] [.N' [.N cat ] ] ] ] ] ] ] ]


\end{tikzpicture}
\end{document}
