There are multiple traditions about where to divide the aliyot for the Shabbat reading of Parashat Bereshit.
The Stone Edition of the Chumash, the Tikkun Torah Lakorim (Ktav Publishing) and several Internet sources (Hebcal, Sefaria, Tikkun.io, Chabad, Wikipedia) begin the sixth aliyah at verse Genesis 4:23, immediately following a short fifth aliyah (4:19-22).
However, several sources use an alternate tradition with a longer the fifth aliyah (ending at 4:26) and begin the sixth aliyah at 5:1. The Koren Humash, the Hertz Humash (The Pentateuch and Haftorahs: Hebrew Text English Translation and Commentary) and Etz Hayim: Torah and Commentary (Jewish Publication Society), and the Rabbi Miles Cohen Luaḥ Hashanah all use this aliyot division.
There is no “correct” answer here. One can argue about which is preferred, but one is not “better” (i.e. more halakhic or more traditional) than the other.