What color is the lightest, mass and weight-wise?

photons are massless and do not have "size" in the classical sense - your question seems highly bizarre.

edited to add, 3 days later:

photons are the particles which our eyes detect and our brains perceive as visible light. Special Relativity says that anything with mass (i.e something which can be weighed) cannot reach the speed of light - so clearly light is weightless. And since colours are different kinds of light, each colour clearly weighs nothing. Not just a very small number like a few milligrams - they weigh *Nothing At All*

Alternatively,

You may be meaning the pigments/paints which make you see different items as certain colours. Some pigments may well be lighter than others, but since there are several different ways of making a particular colour of paint for instance, some of which are denser than others, nobody has enough data to draw any conclusion as to which the densist (and therefore heaviest per unit volume) is.

Photons do not have mass. Violet however, has the shortest wavelength in the visible spectrum while red has the longest wavelength.

Colours are properties of light which has no mass but it does have energy (which is really the same thing)  The energy of light depends on its frequency or wavelength.  The smaller the wavelength the higher the energy.  For the colours of the rainbow red is the lowest energy and violet is the highest.  The approximate wavelengths are:
red - 700 nanometers (billionths of a meter)
orange - 650 nanometers
yellow - 600 nanometers
green - 550 nanometers
blue - 500 nanometers
violet - 400 nanonmeters

If you want you can consider the mass equivalence of a photon of light.  For example, the "lightest" light would be red.  The energy of a photon of red light is

E = hc/lambda
E = 2.84 x10^-19 joules

E = mc^2 so this energy is equivalent to about
3.2 X 10^-36 kg
thats 0.0000000000000000
00000000000000000032 kg