We report on the experimental observation of a color domain (CD) phenomenon in a dissipative soliton fiber laser. The CDs are constituted by a wavelength-dependent condensed phase of pulses in motion. Single CD, dual CD, and tricolor domain that occupy all the cavity space are observed. The CDs have flexible tunability of duty cycle, amplitude, wavelength, and wavelength spacing. The CDs derive from the wavelength-dependent slow evolution of gain, and the formation mechanism of multiple CDs can be explained by cross gain saturation.