When I learnt to play piano as a child I had a simple tune book that started off with the different notes in different colours. Gradually as you went through the book they turned black and (hey presto) I was reading music. I don't know whether colours might help with the dyslexia. If so you could probably get music already coloured in....
Ah ha! I wasn't alone thinking this and apparently it can help:
this instructables suggests chosing the colours that work for you and just colouring the notes - all the As one colour, Bs another colour etc. Apparently making a copy of music for dyslexic individuals is fine in the UK. There is more advice on
the British Dyslexia Association page on music. Not one approach suits all.
I suspect that there are probably on line sites to help read music, although other instruments might be more tricky to visualise than keyboards.