I did an experiment in the classroom yesterday making some hydrogen and it was colourless, but that isn't what the colours of hydrogen are all about. Most of all our hydrogen - a safe clean gas to burn for energy is called Brown Hydrogen, made from Fossils fuels and in the manufacture of this lots of Carbon and other toxic substances like sulfur are produced and typically these are left as pollutants into the air. So although you may be using a clean fuel - hydrogen - its manufacture certainly wasn't clean and green and efficient in any way.
Blue Hydrogen is made in exactly the same way as the Brown Hydrogen, but some of the Carbon and Sulfur are recovered and stored, usually in the ground. The exact amount varies so some hydrogen made this way is very blue and some much less so.
The last type of hydrogen is Green Hydrogen - made from the electrolysis of water using electricity from renewable sources - Wonderful - but it still isn't as Green as it could be because how much Greenhouse gases were using in the manufacture of the renewable energy machines and for the transport and storage of the hydrogen. Perhaps we should call this Cyan Hydrogen. Hydrogen is notoriously difficult to store as being a very small molecule it can escape a solid pipe and in some gas lines as much as 10% of the Hydrogen escapes.