"善用色彩者" can be translated into English as "one who is adept at using colors" or more concisely as "a master of color utilization".
Here are some alternative expressions with slightly different nuances:
"A skilled color user" (emphasizes skill in using colors)
"An expert in color application" (highlights expertise in applying colors)
"A proficient color manipulator" (suggests skillful handling or manipulation of colors, though this may carry a slightly more technical or artistic connotation)
For a more poetic or artistic touch, you could also say:
"A connoisseur of color" (implies a deep appreciation and understanding of colors)
However, the most straightforward and commonly used translation would likely be "one who is adept at using colors" or simply "a master of color" (if the context allows for a more concise expression).