You could colorize all the icons with ImageMagick. See here
[link]Or, as the author of that nice utility told me, you could save this bash script to a file in the top level of the extracted icons folder, make it executable and run it. Just change the relevent numbers:
#!/bin/bash
#Red = 0,61,61
#blue = 61,61,0
#green = 61,0,61
#yellow = 0,0,100
find -iname "*.png" -o -iname "*.svg"| while read file
do
if [ ! -L "$file" ];then
echo Converting "$file" ...
convert "$file" -colorize 61,0,61 "$file"
fi
done