Per request, I have taken some detailed photos of two of my dragonfly specimens, both members of the family Libellulidae. The name of the order is actually based on their strong, chewing, toothed mandibles - "odonto" is Greek for "teeth". The diagrams are taken from Borror and Delong's Introduction to the Study of Insects, 7th Edition.
The relevant abbreviations from above - 1st diagram: lg, ligula or median lobe; mn, mentum; p, palp or lateral lobe; plg, palpiger or squama; 2nd diagram: fr, frons; pclp, postclypeus; aclp, anteclypeus; lbr, labrum; md, mandible; mx, maxilla; lbm, labium; e, compound eye;
I should add that the characteristic which distinguishes Odonata from other insect orders is the location of the copulatory organs, which are located on the anteior end of the abdomen on males, on the underside between the second and third segments. Due to the location, when dragonflies mate their bodies form a circle, known as the "wheel position".