There is much contention over the correct use of the word myriad. People argue over whether to use the word 'of'. For example:
A: There are myriad stars in the sky.
B: The tailors had to sew a myriad of sequins on the ballgown.
In fact, both are correct.
In option A: 'myriad' has been used as an adjective and there is no need to use the word "of".
In option B: 'myriad' has been used as a noun and we use the word "of" in the same way as we would write, "flock of sheep."