Petford and Welsh introduced a sequential heuristic algorithm for (approximately) solving the NP-hard graph coloring problem. The algorithm is based on the antivoter model and mimics the behaviour of a physical process based on a multi-particle system of statistical mechanics. It was later shown that the algorithm can be implemented in massively parallel model of computation. The increase of processing power in recent years allow us to perform an extensive analysis of the algorithms on a larger scale, leading to possibility of a more comprehensive understanding of the behaviour of the algorithm including the phase transition phenomena.