The ornamental design for the personal diffuser holding device, as shown.
FIG. 1 is a perspective view of the personal diffuser holding device;
FIG. 2 is a perspective view of the personal diffuser holding device with a necklace chain coupled thereto;
FIG. 3 is a back view of the personal diffuser holding device;
FIG. 4 is a front view of the personal diffuser holding device;
FIG. 5 is a right side view of the personal diffuser holding device; and,
FIG. 6 is a left side view of the personal diffuser holding device.
The broken lines showing a personal diffuser and other sections of the holding device structure is for the purpose of illustrating a position of the holding device with respect to the personal diffuser and forms no part of the claimed design.