The color of each curve reflects what your eye perceives.
An ideal blackbody radiates power according to the Stefan-Boltzmann law:
Radiation Power = Temperature^4 * SurfaceArea^2 * 5.7*10^-8 Watts/K^4/m^2
The radiation is centered around a characteristic wavelength given by Wein's law:
Wavelength * Temperature = 2.90*10^-3 meter Kelvins
Temperature Radiation Relative Wavelength
(K) (meters) intensity
Earth 287 1.0*10-5 1 Infrared
Sun 5777 5.0*10-7 164000 Visible
The "Blackbody" simulation at phet.colorado.edu shows the blackbody radiation
spectrum as a function of temperature.

Blackbody radiation

f = Photon frequency
h = Planck constant
= 6.62e-34 Joule seconds
E = Photon energy
= h f
C = Speed of light
I = Blackbody photon intensity as a function of frequency
k = Boltzmann constant
= 1.38e-23 Joules/Kelvin
T = Temperature
The Planck law for the blackbody spectrum is
I = 2 h f^3 C^-2 / [exp(hf/kT) - 1]