Key is to not assume that all pigments will have the same impact on the water to cement ratio. Pigments have particle size distribution differences and particle shape differences that affect the properties of concrete due to these differences AND as saturation levels are approached for each type of pigment.
An 8 % loading of Yellow Oxide used at a set W/C ratio vs 0.2 % Carbon Black - Carbon will behave quite normally vs the high dose Yellow "traditional" Oxide - w. everything being equal.
Yes some Blues will affect cure times at higher loadings if water is not compensated. To say exactly how much is very dependent on mix design. Bright Red Liquid color at high loading can impact total water and reduce demand by over 20 %.