PHAK is not clear about VFR flying into Warning Areas. Warning areas are similar in nature to restricted areas, which says IFR can be cleared through the airspace but VFR is not mentionned.
Sectional uses the same visual cue as Prohibited and Restricted but that's a little thin to draw conclusions.
AIM says Prohibited and Restricted are ruled by 14 CFR Part 73 but nothing seems to rule Warning Areas: Warning areas, military operations areas (MOAs), alert areas, and controlled firing areas (CFAs) are nonregulatory special use airspace.
Do you need clearance to fly VFR into a Warning Area?