Upload an image from your computer and choose how many sheets wide you would like your poster to be once printed. Once you're happy with your selection, you can download the PDF file containing your newly created images and print each one massively blown up, resulting in a huge pixel poster to stick on your wall.
Lightshot is a great tool for making screenshots. I actually use it to capture those screenshots I share with you here. Lightshot is available for both Mac and Windows. Once you get it installed , head over to the infographic you want to print and take screenshots of all its parts. Print out each part separately and then put them together on a poster board. I know it is a lot of work but at least it worked for me several times.