Shoes can be either of one colour or multi coloured. The shoes should be of similar colour. If one shoe is multi coloured then the other should also be so. It its permissable to wear coloured shoes.
However, in the light of the Hadith, one should not wear shoes of different sizes, wearing shoes of different sizes will be detrimental to the health of the person. Shariat does not want a Muslim must harm himself in any way.