Hear the dirge of Chaos and despair!
Ahem. I was told many times not to mix Sonic Blasters with Blastmasters, and I've found out from personal experience that this is indeed good advice. You could ditch the Cultists to make a little more room for a few separate 5-(or 6-, the number of Slaanesh)man squads of
NMs with either Sonic Blasters or a Blastmaster per squad. The first to deal with hordes of light infantry, the others to drop the bass on heavy infantry and even an
MC or a light vehicle.
Defilers are awesome models, but not great units. You could swap the 2 for 5 (five!) Obliterators and have some spare points to spend on
NMs. Oblits are far more versatile and survivable.
Can't really comment on Chaos Daemons, but I see some synergy going on in the list. With a couple of tweaks it can become a fluffy and dangerous combination.
Rock on!