One possibility would be to use spell tags/descriptors like Monte Cook's Arcana Evolved. AE had a universal spell list across the board for all classes, but spells were put into not only spell levels but also tiers of complexity: i.e., Simple, Complex, and Exotic. Exotic spells generally required a feat to obtain, though they could also be discovered through play. Additionally, spells often had descriptors or tags like Fire, Dragon, Healing, Plant, Electric, etc.
The wizard-like Magister, for example, got access to all Simple and Complex spells up to 9th level. The shamanistic healer Greenbond got all Simple Spells up to 9th level and all Complex spells with the Healing and Plant descriptors up to 9th level as well. Meanwhile, the gish Mageblade only got all Simple spells up to 6th level.
So imagine, if you will, the Sorcerer. Instead of printing a Sorcerer spell list, simply saying that the Sorcerer gets all Simple spells up to 9th level, and then their Draconic Subclass gives them spells with the Dragon descriptor and their Dragon sutype may additionally give them spells with the Fire descriptor.