GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
#g2 f1 6x6 0 0 0 0 -1 0 -1 0 0 0 0 0 0 -1 0 0 0 -1 0 0 -1 0 0 0 0 0 0 -1 0 1 0 0 0 0 0 -1 6x6 -1 0 0 -1 0 0 0 -1 0 -1 0 0 1 0 1 1 0 -1 0 0 0 1 0 0 0 1 0 0 1 1 0 0 0 1 0 -1 6x6 4 1 2 2 1 0 1 4 1 2 2 1 2 1 4 1 2 -1 2 2 1 4 1 -1 1 2 2 1 4 1 0 1 -1 -1 1 4 2^4 * 3 * 5 = 240 dim6/6-4b