public void SetGuideColor( 
   CIMColor color
)

//keep graphic element insert tool active
ApplicationOptions.LayoutOptions.KeepLastToolActive = true;
//no warning when deleting a map frame results in other elements being deleted
ApplicationOptions.LayoutOptions.WarnAboutAssociatedSurrounds = false;
//path to .pagx files used as templates
ApplicationOptions.LayoutOptions.LayoutTemplatePath = @"D:\data\layout_templates";

QueuedTask.Run(() =>
{
  var guideColor = ApplicationOptions.LayoutOptions.GetGuideColor();
  // set guide color
  ApplicationOptions.LayoutOptions.SetGuideColor(ColorFactory.Instance.RedRGB);
});