Find the file tellico-printing.xsl which should be in the $KDEDIR/share/apps/tellico/ directory. You can copy that to $KDEHOME/share/apps/tellico/ for personal modifications. You’ll have to know XSLT, but modifying that file is how you change the printing layout. HTML is generated from the file, and the easiest way to change the appearance of the printout is to modify the CSS in the top portion.
Be aware that the tellico-printing.xsl references another file, tellico-common.xsl, that contains some common XSLT templates. If you copy tellico-printing.xsl to $KDEHOME, you must either modify the element to point to the actual location of the tellico-common.xsl file or copy the common file as well.