#[MATL](https://github.com/lmendo/MATL), <s>36</s> 29 bytes

    5l$rtP+!kllII$r*O16tQ/XE'a'YG

This saves the result in file `a.png`.

Replacing `'a'` by `2` in the code displays the image (scaled up) instead of saving a file:

    5l$rtP+!kllII$r*O16tQ/XE2YG

Here's an example output:

[![enter image description here][1]][1]

###Explanation (to be updated)

    H5H$r    % 2×5 array of independent random numbers with uniform distribution on (0,1)
    l5H$r    % 1×5 array of independent random numbers with uniform distribution on (0,1)
    y        % Duplicate the first array
    P        % Flip vertically
    v        % Concatenate the three arrays vertically. Gives a 5×5 array
    Ek       % Multiply by 2, round down: gives 0 or 1 equiprobably
    !        % Transpose so that the array has horizontal (not vertical) symmetry.
    llII$r   % 1×1×3 array of independent random numbers with uniform distribution
             % on (0,1). This is the foreground color.
    *        % Multiply the two arrays with broadcast. Gives a 5×5×3 array. Ones in the
             % 5×5 array become the random foreground color. Zeros remain as zeros.
    O        % Push 0
    16tQ/    % 16, duplicate, add 1, divide: gives 16/17, or 240/155
    XE       % Replace 0 by 16/17: background color
    'a'      % Push file name
    YG       % Write image to that file

  [1]: https://i.sstatic.net/DI5GG.png