Neural Network color

\documentclass[border=0.125cm]{standalone}
\usepackage{tikz}
\usetikzlibrary{positioning}
\begin{document}

\tikzset{%
   neuron missing/.style={
    draw=none, 
    scale=4,
    text height=0.333cm,
    execute at begin node=\color{black}$\vdots$
  },
}

\begin{tikzpicture}[x=1.5cm, y=1.5cm, >=stealth]

\foreach \m/\l [count=\y] in {1,2,3}
{
 \node [circle,fill=green!50,minimum size=1cm] (input-\m) at (0,2.5-\y) {};
}
\foreach \m/\l [count=\y] in {4}
{
 \node [circle,fill=green!50,minimum size=1cm ] (input-\m) at (0,-2.5) {};
}
 
 \node [neuron missing]  at (0,-1.5) {};
 

\foreach \m [count=\y] in {1}
  \node [circle,fill=red!50,minimum size=1cm ] (hidden-\m) at (2,0.75) {};
  
\foreach \m [count=\y] in {2}
  \node [circle,fill=red!50,minimum size=1cm ] (hidden-\m) at (2,-1.85) {};
  
 \node [neuron missing]  at (2,-0.3) {};


\foreach \m [count=\y] in {1}
  \node [circle,fill=blue!50,minimum size=1cm ] (output-\m) at (4,1.5-\y) {};
  
\foreach \m [count=\y] in {2}
  \node [circle,fill=blue!50,minimum size=1cm ] (output-\m) at (4,-0.5-\y) {};

 \node [neuron missing]  at (4,-0.4) {};

\foreach \l [count=\i] in {1,2,3,256}
  \draw [<-] (input-\i) -- ++(-1,0)
    node [above, midway] {$I_{\l}$};

\foreach \l [count=\i] in {1,16}
  \node [above] at (hidden-\i.north) {$H_{\l}$};

\foreach \l [count=\i] in {1,16}
  \draw [->] (output-\i) -- ++(1,0)
    node [above, midway] {$O_{ \l}$};

\foreach \i in {1,...,4}
  \foreach \j in {1,...,2}
    \draw [->] (input-\i) -- (hidden-\j);

\foreach \i in {1,...,2}
  \foreach \j in {1,...,2}
    \draw [->] (hidden-\i) -- (output-\j);

%\foreach \l [count=\x from 0] in {Input, Hidden, Ouput}
 % \node [align=center, above] at (\x*2,2) {\l \\ layer};

\end{tikzpicture}

\end{document}