Color image segmentation is the process of grouping regions according to some criterium. In this work, we cope with this problem using a graph-based approach based on removal of minimum spanning tree edges, however the tuning of parameters is a difficult task. To better identify the set of parameters which optimizes the error producing good segmentations, we propose the use of genetic algorithm in order to establish the best set of parameters. According to test experiments, our proposed method presents better results when compared to other approaches from the literature.