There does not appear to be any standardised form or iconography for Nivaranavishkambhin. He is most commonly found with the group of the Eight Great Bodhisattvas.
Jeff Watt [updated 8-2018]
Toh 640/880. The Incantation of the One Hundred and Eight Names of Sarvanīvaraṇaviṣkambhin སྒྲིབ་པ་རྣམ་སེལ་གྱི་མཚན་བརྒྱ་རྩ་བརྒྱད་པའི་གཟུངས་སྔགས། · sgrib pa rnam sel gyi mtshan brgya rtsa brgyad pa'i gzungs sngags. sarvanīvaraṇaviṣkambhināmāṣṭottaraśatakaṃ dhāraṇīmantrasahitam.
Toh 891. The Dhāraṇī of Āvaraṇaviṣkambhin. The Collection The Kangyur Dhāraṇī Compendium of Dhāraṇīs. སྒྲིབ་པ་རྣམ་པར་སེལ་བའི་གཟུངས། · sgrib pa rnam par sel ba’i gzungs. Āvaraṇaviṣkambhidhāraṇī. 2 pages.