How do you speak of One of whom no human word or words can contain? One who says rightfully and rhetorically of Himself, “To whom will you compare me?” (Is. 40.25)
I guess you try to go beyond words. Use words to point to something infinitely further.
He is great like nothing else is great. Greater than the greatest that anything or anyone ever will be. He is the mountain range that towers over top of the Himalayas. The light that shines brighter than the brightest stars wrapped around the sun and shining at their brightest. He is that series of notes strung together, more beautiful, melodic, poetic and angelic than our brains can register, than our ears can even hear. He is the colours that sit on a canvas that our eyes aren’t even capable of seeing, much less our minds capable of understanding what it is we see.
He is simply infinitely greater than all that the language of greatness can convey. Maybe that is why John resorted to speaking in precious stones, “And he who sat there had the appearance of jasper and carnelian, and around the throne was a rainbow that had the appearance of an emerald” (Revelation 4.3)