1. An embroidery data generator generating embroidery data on which an embroidery pattern is sewn, the generator comprising: a display unit configured to be capable of color display; and a control device configured to: cause the display unit to display a color chart representing at least one of three attributes of hue, saturation and value of a color in an HSV color space; set a range on the displayed color chart; randomly extract one of colors within the set range, the one color being used as thread color data, the embroidery pattern including a plurality of color-based pattern portions, the thread color data specifying colors of the color-based pattern portions; and assign the extracted color to the thread color data of a corresponding one of the color-based pattern portions.