Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison
Or if you wanted to do something tricky I imagine a digital/inkjet print on tissue would be pretty effective. Seal a piece of floor first, carefully lay it out, squeegee it flat and seal over top.If you had quite light concrete I'd be tempted to give it a go. Be a bit selective with your color choices so you get good contrast.