Warlock Imps are getting 15 customization options in Patch 10.1.5 and here’s a preview of them all along with sources.
Warlocks can customize their pets in the Barber Shop in Fractures in Time.
Imp Customization Options in Patch 10.1.5
Source: Terestian Illhoof
Source: Burning Crusade Timewalking
Source: Legion Time Rifts
Source: Grimoire of the Fel Imp
Source: Default
Source: Found at the Faire
Source: Pusillin
Source: Matron Folnuna
Source: Vi’el
Source: Imp Mother Dyala
Source: Legion Timewalking
Source: Class Quest
Source: Class Quest
Source: Class Quest
Source: Class Quest