That is the big question - just how do you paint planets?
Well, unless there's iron to oxidize on the surface (as in Mars' case), I'd expect rock-type colors, brown or grey. If the atmosphere is dense enough and the temperature's right, you'll have some surface water, which will be blue. (With the pressure's and temperatures you have for your desert planet, I'd almost expect to see more water than ice, at least on the day side. 0.02 atmospheres is above the triple point pressure of water, and a 34C average temperature might mean that few places on the day side are ever below the freezing point).
The big thing is figuring out the materials that make up your surface (rock, ice, whatever), and how they will react chemically with the chemicals in your atmosphere and any rain. This will determine the colors you get.
Anyone seen a "planet making for dummies" book around?
Someone recommended World Building, by Stephen Gillett, to me a while ago, but I haven't bought it yet...
It's the size of Mars, but somewhat denser, with 0.02 atm of air. Molecular limit calculated at 20, no moons, no significant magnetic field.
Makes sense?
Well, the problem is with it being the size of Mars and having a 0.61 g surface gravity. That would require a density of around 6300 kg/m^3, which for a planet of that size would require a huge iron core, taking up more of the planet than even Mercury's core. At that point you might well have a significant magnetic field, although that is not the primary thing working against atmospheric loss. With about 1.6 times the mass and the same surface area, it will start off hotter inside and cool more slowly than Mars, which will mean more gasses released by vulcanism over a longer period, which will mean a somewhat thicker atmosphere.
Then again, with so much iron in the core, I wouldn't be so surprised to see iron on the surface of this particular planet, so it might just have a Mars-like reddish tint...
A more reasonable density for that surface gravity might be somewhere in the 4000's of kg/m^3 (lower 4000's in an iron poor system, higher 4000's or maybe even low 5000's in an iron rich system, or if the planet has had alot of its mantle blown away by some impact. I'd say 4500 is a fairly reasonable density to expect, though the average might be a bit higher or lower). Assuming a density of 4500, you get a radius of about 4750 km, and a mass of about 1/3 Earth's. Escape velocity is then about 7500 m/s. The higher escape velocity should work against atmospheric escape.