Assuming the likelihoods have been calculated correctly, you could divide each of them by the largest likelihood. That can be done in logarithm form by subtracting the largest log-likelihood from each log-likelihood.
You can then convert out of logarithm space. The largest will be 1.0, because its normalized log is 0. The smaller ones will each be between 0 and 1.0, and represented as a fraction of the largest.