Pool plaster is a type of concrete, in other words, a mixture of white Portland cement (itself a mixture of marble, limestone, shale ground to a fine powder and mixed again with gypsum), aggregates, and curing additives. The aggregate in the common concrete used for foundations and sidewalks is stone gravel in various sizes. However, in pool plaster the aggregate is fine quartz sand or marble dust. Quartz sand makes a more durable plaster, but the downside is it has lower workability. The curing additives include chemicals such as calcium chloride, calcium sulfate, or lime. Portland cement's setting and curing is a highly complicated chain of sequential chemical reactions, which is the reason that full strength takes a number of days to develop.
All of which is to say that working with pool plaster is a lot like working with concrete; exacting in its timing and unforgiving of any mistakes. Consider sub-contracting this part of your plaster finish swimming pool construction or renovation project out to a professional. They will handle the mixing of the plaster, ensuring the proper type is used for your local construction codes, spraying on of the plaster to the required thickness, and even the clean-up and disposal of left-overs.
For pool plaster colors, there is an assortment of additives to the basic white mix described above. One type is dyed quartz in single or multiple colors. Quartz adds a more textured surface to your pool as well as durability. Another type of pool plaster color is the dye additives which give a grey or black color to the pool surface.
If you still want to do it yourself, here is a rough outline.
You will need a concrete mixer (a mortar mixing machine would be even better if you find one), stainless steel pool trowels and other plaster tools, and a couple of tons of pool finish plaster.
Before you apply the new plaster, you will need to ensure the pool surface is thoroughly prepped, which means a lot of time and effort for refinishing an old pool. All areas of loose plaster must be identified and removed by chipping off with hammer and chisel or smaller pneumatic hammer. The removed areas and any other holes or depressions must be spackled in and the edges feathered to present a consistent surface for the finish plaster.
You will also want to practice your hand troweling some before you start the big job. What you will be aiming for is a consistant layer of from ¼ inch to ½ inch with as little variation as possible. The more skilled you get as a plasterer, the less variation in thickness you will have. Working the plaster on in small sections at a time helps break the work up into manageable chunks.
After the plastering is finished and any imperfections have been ground away and and repaired, the plaster must be allowed to cure for a certain amount of time, depending on the type used.(Except for wet-cure plaster, which sets underwater, so you begin to fill the pool as soon as the plastering is completed).