I'm with Ed on this. It's best NOT to go by color alone. As it happens, the long life OEM Nissan coolant is blue #L25500P - it is already diluted 50/50 as required. Nissan also makes a green coolant that is 100% concentrated and must be diluted before use. Perhaps Ed can clarify, but I believe the green coolant is made for ATVs, utility vehicles, motorcycles, snowmobiles, etc. Not sure if the green coolant is best for your car engine.
You can buy Nissan coolant anywhere - Ebay, Amazon, etc for about $20 per gallon. The dealer is a good place to get it too, but make sure they don't try to charge their usual mark-up and hit you for $40 or some ridiculous price.
Either way, I do not recommend using auto parts brands for any of the fluids in your car. I'm not saying they aren't good, or are unsafe. I think of it this way: Even if you pay $5 more per gallon for OEM fluids, it's an expense that comes up every 5 years, so don't sweat it.