\documentclass[border=5mm]{standalone}
\usepackage{luamplib}
\begin{document}
\begin{mplibcode}
input colorbrewer-rgb
beginfig(1);
path o; numeric r; r = 1/4;
o = (for i=0 upto 3: subpath (i+r, i+1-r) of unitsquare shifted -(1/2, 1/2) -- endfor cycle) scaled 42;
picture unit; path s; s = unitsquare scaled arclength subpath (1, 3/2) of o
rotated -45 shifted point 3/2 of o;
unit = image(
fill o withcolor Blues 8 5;
for i=0 upto 3: fill s rotated 90i; endfor
);
pair u, v; u = 42 right; v = u rotated 90; numeric n; n = 3;
for i=-n upto n:
for j=-2n upto 2n:
draw unit if (i+j) mod 4 < 2: reflectedabout (dir 135, dir -45) fi
shifted ((2i + j mod 2)*u + j*v);
endfor
endfor
