CColorDialog colorDlg;

colorDlg.m_cc.Flags |= CC_RGBINIT;  

colorDlg.m_cc.rgbResult = this->m_nColor; //记录先前选择的颜色

if( colorDlg.DoModal() == IDOK )

   this->m_nColor = colorDlg.m_cc.rgbResult; //获取用户选择的颜色