Project project = new Project("New Project.mpp");
SaveOptions options = new PdfSaveOptions();
options.PresentationFormat = PresentationFormat.ResourceSheet;

TextStyle style = new TextStyle();
style.Color = Color.OrangeRed;
style.FontStyle = FontStyle.Bold;
style.FontStyle |= FontStyle.Italic;
style.ItemType = TextItemType.OverallocatedResources;

options.TextStyles = new List<TextStyle>();
options.TextStyles.Add(style);
project.Save("CustomizeTextStyle_out.pdf", options);