Yes, 1 part sugar to 4 parts water is what is recommended by ornithologists, including the Cornell people. No food coloring necessary to attract hummers to a feeder - they are smart little things and they know a feeder when they see it, no matter what shape, size or color it is or what color the nectar is.
I recommend boiling the water and sugar mixture up. I use a pyrex tea kettle and can make just over 7 cups of nectar at once (barely a 3-day supply for my 4 feeders this time of year!). In my experience, the boiling gets rid of any bacteria or other negative things in the tap water and boiled nectar keeps for at least a week in the fridge. It also seems to not get yucky as fast in the feeders, although I clean and refill my feeders every 3 days, empty or not... although right now, it's sometimes daily or every other day because of the rate of nectar consumption.