We can say for sure all beauty comes from Hashem, but how it relates to him I'm woefully unqualified and suspect we all are and might be until moshiach comes, but regardless beauty involves matter made on way or another, existing in time. These are concepts Hashem controls in ways we can't understand, and in the morning shabbat prayers we say "beauty and victory to Him who lives forever", so we know beauty is in his possession, but to say He is beautiful I'm not sure that's a complete way to say it even if it may be right in a simple kind of way.