Hello,
This is the phpdoc of the method addTableContents:
/**
     * Add a table of contents (TOC)
     *
     * @access public
     * @example ../examples/easy/TableContents.php
     * @param array $options
     *  Values:
     * 'autoUpdate' (boolean) if true it will try to update the TOC when first opened
     * 'displayLevels' (string) must be of the form '1-3' where the first number is
     * the start level an the second the end level. If not defined all existing levels are shown
     * @param (array) $legend
     * Values:
     * 'pStyle' (string) Word style to be used. Run parseStyles() to check all available paragraph styles
     * 'b' (on, off)
     * 'color' (ffffff, ff0000...)
     * 'font' (Arial, Times New Roman...)
     * 'i' (on, off)
     * 'indent_left' 100...,
     * 'indent_right' 100...
     * 'jc' (both, center, distribute, left, right)
     * 'keepLines' (on, off) keep all paragraph lines on the same page
     * 'keepNext' (on, off) keep in the same page the current paragraph with next paragraph
     * 'lineSpacing' 120, 240 (standard), 480...,
     * 'pageBreakBefore' (on, off)
     * 'sz' (8, 9, 10, ...)
     * 'text' (string)
     * 'u' (none, dash, dotted, double, single, wave, words)
     * 'widowControl' (on, off)
     * 'wordWrap' (on, off)
     * @param (string) $stylesTOC path to the docx with the required styles for the Table of Contents
     */
As you can see there're options to change color, align, size...
Regards.