/usr/share/gnuplot/pm3d/colorpts-demo.gp is in gnuplot-qt 4.6.4-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | #set pal gray
#set pal color; set palette rgbformulae 3,11,6
set pm3d map
splot '<awk -f colorpts.awk pts.dat 0.07 0.07'
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