The easiest way is to use multiple condition formats instead of the 3 color scale option.
In separate cells create the LARGE formulas to return the 1st, 2nd and 3rd rank values - e.g. =LARGE($G$2:$G$251,1) for 1st etc.
On the range of results, create 3 different conditional formatting rules whereby the value equals each of the rankings to color the cells. This will result in the third ranking only coloring the cells for that value and not the rest.
This approach will also enable to provide an area with the summary of results (1st, 2nd and 3rd) optionally with a VLOOKUP with names against them, and can also be extended for 4th, 5th position rankings and so on.
